U.S. patent number 4,051,522 [Application Number 05/574,315] was granted by the patent office on 1977-09-27 for patient monitoring system.
This patent grant is currently assigned to Jonathan Systems. Invention is credited to Bob L. Currier, James W. Healy.
United States Patent |
4,051,522 |
Healy , et al. |
September 27, 1977 |
Patient monitoring system
Abstract
Disclosed is a hospital patient monitoring and display system
employing a number of bedside consoles, concealable from the
patient and including input for various patient sensors such as
ECG, pulse rate, patient temperature and blood pressure. The
consoles are powered by a low voltage direct current supply at a
central station. The central station includes signal processing and
display apparatus to allow the patient data to be displayed on a
conventional commercial black and white or color television set
along with alpha numerics related to each respective patient. The
display is coupled to the hospitals normal entertainment television
distribution network, if any, allowing the patient data to be
displayed on any television set throughout the hospital. The signal
processing and display portions of the system include a control to
vary the trace speed and to freeze a display. A printer is
connected to the display system to automatically print a
reproduction of the display whenever the "freeze" control is
actuated. A remote control operation via a radio frequency link may
be carried by a patient's doctor and may be operated at any time or
place within reception range of the central control to freeze the
display for better examination and automatic printout of a
reproduction. After a preset period, the display resumes. The
system includes controls for setting maximum allowable values of
various parameters and for sounding an alarm whenever the patient
parameter varies from the allowable value. Such variation is
registered as a shift from one color display to a different one in
the case of color television sets, e.g. normal trace, green and
abnormality, red. In the case of black and white displays, an alarm
condition may be represented as intensity modulation or flashing of
the display.
Inventors: |
Healy; James W. (Malibu,
CA), Currier; Bob L. (Gardena, CA) |
Assignee: |
Jonathan Systems (Los Angeles,
CA)
|
Family
ID: |
24295588 |
Appl.
No.: |
05/574,315 |
Filed: |
May 5, 1975 |
Current U.S.
Class: |
725/78; 348/473;
348/61; 348/705; 128/903; 715/733; 346/33ME |
Current CPC
Class: |
A61B
5/02 (20130101); A61B 5/002 (20130101); Y10S
128/903 (20130101) |
Current International
Class: |
A61B
5/02 (20060101); A61B 5/00 (20060101); H04N
007/18 () |
Field of
Search: |
;178/6.8,DIG.13
;340/324AD ;128/2.1A ;312/7,204,209,210,242,7 ;325/352,353
;343/225,228 ;358/86,93,142,181 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Britton; Howard W.
Attorney, Agent or Firm: Wagner; John E.
Claims
What is claimed is:
1. A patient monitoring system comprising a central control console
including:
a. a power supply;
b. a controller for establishing alarm limits for patient data;
c. a video translator for converting patient analog date into video
traces representative of the analog values thereof;
d. keyboard means for generating alpha numeric data;
e. means for combining alpha numeric data with said video traces of
patient analog data;
f. means for introducing said combined data into a television
distribution medium;
at least one patient station including means connectable to patient
sensor for amplifying a patient parameter sensor to a predetermined
level;
said amplifying means powered by said power supply of said central
control console;
means conducting said amplified parameter to said central control
console;
wherein said video translator includes means for storing analog
patient data for a selected period of time and for introducing said
data into said distribution system at the end thereof; and
wherein said video translator includes means for establishing a
WRITE and an ERASE cycle, including switch means for temporarily
terminating the WRITE and ERASE cycle of said video translator and
for enabling said recorder to record the analog data stored in said
video translator.
2. The combination in accordance with claim 1 wherein said console
includes an R.F. receiver and wherein said switch means is
responsive to signals detected by said R.F. receiver and portable
R.F. transmitter for generating and transmitting a signal to said
R.F. receiver.
3. A patient monitoring system comprising a central control console
including:
a. a power supply;
b. a controller for establishing alarm limits for patient data;
c. a video translator for converting patient analog data into video
traces representative of the analog values thereof;
d. keyboard means for generating alpha numeric data;
e. means for combining alpha numeric data with said video traces of
patient analog data;
f. means for introducing said combined data into a television
distribution medium;
at least one patient station including means connectable to a
patient sensor for amplifying a patient parameter sensor to a
predetermined level;
said amplifying means powered by said power supply of said central
control console;
means conducting said amplified parameter to said central control
console;
wherein said video translator includes means for storing analog
patient data for a selected period of time and for introducing said
data into said distribution system at the end thereof; and
wherein said video translator includes means for varying the
horizontal sweep rate of said analog data stores therein.
4. A patient monitoring system comprising:
a patient station including a recessed wall mounted console;
said console including a plurality of amplifiers and connector
means for said amplifiers to interconnect said amplifiers to
patient sensors;
a central control console located remote from said patient
station;
said central control station including power supply means for
operating said amplifiers;
cable means for supplying power from said control console to said
amplifier means and to conduct physiological signals from said
amplifiers to said central control console;
means at said central control station for translating physiological
signals received from said patient station into video format;
means for generating alpha numeric information;
means combining video formatted physiological information with
alpha numeric information into a display with each visually
associated together and means for conducting said combined display
to at least one television monitor;
including printing means including a second monitor, said printing
means responsive to command to print a copy of the information
displayed on said second monitor; and
switch means for commanding the operation of said printing
means.
5. The combination in accordance with claim 4 wherein said switch
means comprises;
a switch connected to said printing means;
a video frequency receiver connected to operate said switch upon
receipt of a command signal; and
a portable radio frequency transmitter for generating such command
signal.
Description
BACKGROUND OF THE INVENTION
Classically, hospital patient monitoring systems have involved the
use of patient sensors connected to local signal processors powered
by standard power mains (115 volts AC) and connected via
communications cables to a central system for display. Typically,
such displays have been medical cardioscopes and other specialized
displays.
One of the major limitations on such systems is the need of each
patient station to provide absolute isolation between the 115 volt
AC supply and the patient to whom a few microamperes of leakage
current may prove fatal. Extensive patient isolation apparatus has
therefore been absolutely mandatary for each bed.
One of the other limitations is the specialized displays being
expensive, are usually available only at the patient monitoring
station where they are grouped for monitoring by one or more
attendants. An alarm condition of one of several patients is
difficult to visually and audably isolate and in general is
extremely difficult to monitor effectively.
A number of patents illustrate systems of the above type.
Representative are:
______________________________________ 3,690,312 B. H. Weppner et
al Sept. 12, 1972 3,779,237 R. R. Goelte et al Dec. 18, 1973
3,536,062 A. J. Horn Oct. 27, 1970 3,545,429 E. R. Penta et al Dec.
8, 1970 3,584,618 C. J. Reinhard et al June 5, 1971
______________________________________
Certain patents have disclosed the use of radio frequency links in
patient telemetry systems either between the patient and a local
antenna or between the patient and a central monitoring
station.
Such patents are:
______________________________________ 3,638,642 A. E. Heflin Sr.
Feb. 1, 1972 3,646,606 R. L. Buxton et al Feb. 29, 1972 3,603,881
W. E. Thornton Sept. 7, 1971 3,639,907 W. Greatbach Feb. 1, 1972
______________________________________
A patent disclosing the use of conventional commercial television
sets for display of patient monitoring data is:
______________________________________ 3,530,236 A. R. Marko Sept.
22, 1970. ______________________________________
It has also been proposed in one publication, namely Biophysical
Measurements, by Peter Strong, published in November, 1970 by
Tectronix, Inc. that low cost television sets may be employed for
display of patient data throughout a hospital. It was suggested
therein that an alarm condition could be made to trigger a recorder
to produce a permanent record of the patient data.
BRIEF DESCRIPTION OF THE INVENTION
We have produced a patient monitoring system employing low voltage
patient bedside consoles and a central, isolated power supply,
signal processing and display station. The displays are
conventional television sets, color or black and white and
connected to the system through the normal television distribution
system. Unused entertainment channels may be used for patient data
display.
The system includes a patient station totally mounted in the wall
at patient bedside and concealed when not in use by an attractive
framed picture which is removable to allow use of the patient
station. All power to the patient station is low voltage which is
isolated at the central power supply from the A.C. mains. Further
isolation occurs at the patient station.
Each patient station is designed to mount up to four modules
depending upon the particular needs of the hospital or the
particular patient and each station includes local outputs for
T.V., oscilloscope, computer or recorder. Each patient station is
connected to the power supply and central station by simple twisted
pair or coaxial of communications type cabling.
One feature of this invention involves a presence of a non-fade
display of patient data in a video format. Another feature of this
invention involves a manual control to freeze the present display
and to automatically print out a permanent record of the display
each time the freeze control is actuated.
Still another feature of this invention involves a remote
controllable radio frequency link to the central control station
allowing the patient's doctor to freeze and print out a record of a
present display from any place within range of the remote video
link.
One other feature involves the provision for superimposing of
pictorial and alpha numeric information whereby X-rays and other
pictorial displays may be presented, for example, to an operating
surgeon, immediately upon processing at the X-ray laboratory along
with patient identification information.
BRIEF DESCRIPTION OF THE DRAWING
The above features of this invention may be more clearly understood
by the following detailed description and by reference to the
drawings in which:
FIG. 1 is a perspective view of a hospital installation
incorporating this invention;
FIG. 2 is a simplified block diagram of this invention;
FIG. 3 is a more detailed block diagram of this invention;
FIG. 4 is a continuation of FIG. 3;
FIG. 5 is an arrangement of FIGS. 3 and 4;
FIG. 6 is a graphical display in accordance with this display;
FIG. 7 is an electrical schematic diagram of a patient amplifier
module in accordance with this invention; and
FIG. 8 is a block diagram of the video translator of the system of
this invention.
DETAILED DISCLOSURE OF THE INVENTION
Continuous real time monitoring of hospitalized patients has
developed in the last few years to the level where every hospital
must have several monitored beds in at least the intensive care and
cardiac care wards. Such systems must be flexible to adapt to new
types of sensors, to add to the diagnostic inputs and similarly the
displays must be meaningful, unambiguous and clearly identify
abnormalities in any of a number of patients without deluging the
nursing staff and physicians with records of insignificant data. A
need exists for real time, continuous patient data combined with
alpha numerics available to monitoring nurses and to the patient's
doctor on a near instantaneous basis and for permanent records of
data of interest or abnormalities.
Now referring to FIG. 1, a single bed of a multiple bed
installation employing this invention is illustrated along with the
central monitoring system and a remote monitor. At the patient
station a conventional bed 10 is located against a wall 11 mounting
over the bed lighting 12 and a patient monitoring recessed cabinet
13 containing a number of physiological monitoring modules 14-17,
all connected by individual or common cable connection 18 to the
patient 20. The modules 14-17, for example, may monitor and display
in digital form:
Heart rate;
Systolic Arterial Pressure
Mean Arterial Pressure;
Venous Pressure;
Temperature;
or other parameters which may be required to be monitored and
displayed. The modules 14-17 are not normally visible to the
patient although in direct view of an examining physician or nurse
at bedside. When not in use, the cabinet 13, in actuality,
constitutes the frame of an attractive picture which is insertable
in the frame and becomes an unobtrusive portion of the room decor.
This is illustrated by the adjoining cabinet 21 with the picture 22
in place. Although the intensive and cardiac care rooms are
normally rather heavily instrumented and patient apprehension of
such equipment is not a factor, the form of patient cabinets herein
disclosed allows the installation of patient monitoring of the most
sophisticated type in any conventional patient room and its
concealment when not in use.
The fact is that each patient station only involves the basic
installation of a cabinet 13 plus cabling 23, shown in dashed
lines, since it is hidden in the wall 11. Modules 14-17 may be
installed at any time and patient sensors unshown in the drawing
are available for connection over a cable similar to cable 18.
All power to the modules 14-17 and the sensors, if needed, is
supplied over concealed cable 23 from the central station 24,
represented by console 25, which contains all but the patient
station components of the system.
The central station 24 includes the console cabinet 25 including a
pair of television monitors 26 and 30, each capable of displaying
physiological and alpha numeric data of four patients for a total
of 8 patient stations per console. A keyboard 31 is present and
used to insert alpha numerics into the display such as the patients
name, bed or room number and to manually insert physiological
parameter limits such as heart rate or blood pressure. The console
25 also includes an analog recorder which continuously or on
command produces an analog trace 32 of physiological data of a
selected patient as determined by patient selector switches 33. A
video printer within or associated with the console 25 produces
printouts of the actual video displays. Also contained within the
console 25 are the power supply, signal conditioning apparatus,
logic circuitry and an R.F. receiver 34 and its associated antenna
35. The R.F. receiver 34 and antenna 35 cooperate with one or more
portable signalling transmitters 40, one of which is shown in the
hand of a physician 41 who is observing physiological data of his
patient on one of many entertainment television sets 42 in a modern
hospital. The physician 41 has operated the channel selector of the
television set 42 to a preselected, unused entertainment channel
displaying his patient or the patient of interest. His control 40,
through an R.F. link to the central control console 24, actuates a
"freeze" control which holds the present trace on the video screen
for a controlled or preselected period, e.g. 60 seconds. Responsive
to the actuation of the freeze control 40 or a similar manual
control at console 25, the video printer is enabled and prints a
permanent record of the video display at the same instant.
Employing this feature, a physician may monitor his patient at any
place where a commercial television set is present in the hospital,
freeze a trace at any time to examine it for several seconds and
obtain a permanent record, upon returning to the central control
station.
The above is all accomplished employing the system of FIGS. 2 and
3. FIG. 2 shows the basic system as applied to a four bed
installation with one cabinet 13 a, b, c or d for each bed, each
supplied with power over conductors 23p and each transmitting
physiological data over leads 23a-d respectively. All leads 23 may
be gathered in one bundle and conducted in the manner of low
voltage and communications conductors rather than power
cabling.
Each patient station may have a physiological monitor or
entertainment television set 19a-d, served usually by a central
cable distribution cable 43 or in certain cases, by its own antenna
as in the case of the monitor 19 of FIG. 1. If additional bedside
apparatus is required for an individual patient, the cabinets 13a-d
include jacks for such use, for example, recorders, computers or
oscilloscopes for direct coupling rather than through the central
control station.
The signal conductors 23a-d are connected through selector switches
50a-d to a video translator 51 and the controller and recorder 52
of the central console. The branch circuits 123a-d provide real
time signals to the controller and recorder 52 to allow actuation
of alarms where preset limits are exceeded and the recording of
real time data on recorder 32a.
The video translator 51, constituting a significant feature of this
system, stores and converts bedside waveforms to a non-fade video
picture. The video translator 51 receives analog waveform inputs
from each bed, samples and stores the analog signals, combines the
traces within conventional television horizontal and vertical sweep
signals to form a EIA video output for display on monitor sets on
any conventional television set. The sweep rate is adjustable from
e.g. 1 to 120 seconds per sweep. The translator also includes a
"freeze" control shown in FIG. 3.
The video translator 51 is connected via a keyboard assembly 53 for
adding alpha numerics to the traces and thence via lead 54 to a
junction box 55. This junction box 55 serves to introduce signals
from this system into the entertainment television transmission
system of the hospital including cable 43 and a common antenna 56.
The monitor 26 of FIG. 1 is connected to the box 55.
With the system in this form, monitored patient data is amplified
to standard levels, e.g. 1.V., at each wall cabinet 13 and
transmitted via conductors in analog form to the controller and
video translator. There the signal is used in its new form to
actuate alarms as required and is also stored and converted to
video format for introduction into the hospital entertainment
television system. Alpha numerics to identify patients and to
provide other data are added at the central station via the
keyboard. The central control supplies power for the patient
monitors as well as the controller and video translator.
The foregoing is the basic system of this invention, however, an
operational system preferably includes additional features better
shown in FIGS. 3 and 4. In these figures, identical elements to
FIGS. 1 and 2 employ identical reference numerals. FIGS. 3 and 4
are arranged as shown in FIG. 5.
Now referring to FIGS. 3 and 4, the bedside station for a four bed
installation includes, in addition to the cabinets 13a-d, an
optional closed circuit television camera 100 directed toward the
cabinets 13a-d or the patients for direct live monitoring of the
bedside conditions over leads 101. Analog patient data from the
sensors connected to the patients from the four cabinets 13a-d are
again transmitted on lead 23a-d to an interface assembly 102 or
distribution panel. In this case binary coded decimal data (BCD) is
additionally available from bedside modules representing such
parameters as heart rate and patient temperature. These BCD signals
are available where the individual modules of the cabinets 13a-d
generate such signals for example, to display such parameter at the
bedside in digital form. The same circuitry used to display these
parameters applies to the BCD signal to lead 103 for use or display
at the central control station. D.C. power for all bedside modules
again is supplied over lead 23p from the central power supply
27.
In many instances the patient may be monitored via a R.F. telemetry
link while wearing a telemetry transmitter 104. A telemetry
receiver 105 is then connected to the leads 23 or 103 depending
upon the nature of the signal from the patient. It is usually in
analog form. The telemetry receiver may include counters and
provision for under or over count limits, for example, upper and
lower heart rate limits and transmit an alarm condition signal
only. This arrangement is represented by the heart rate limit
controls 106. The foregoing constitutes a novel bedside
installation.
The central control console is connected to the bedside
installation via the interface assembly 102. The output of the
interface assembly 102 to the central console constitutes analog
data on leads 110 and 111 and binary coded decimal data on leads
112 and 113. The analog signals on lead 110 are introduced into the
video translator 51 which both stores the analog signal for periods
of up to 120 seconds and converts it to commercial video format
including synchronized horizontal and sweep signals. The lead 110
represents four leads from individual beds and these signals are
all converted and placed in video format for display in vertical
array on the face of a commercial display 26 in the console and at
bedside displays 19 after combining in a video mixer 114 and
amplification in video display distribution amplifier 115. The
mixer 114 also combines the closed circuit TV input where used from
a selector 116 to display bedside scenes where desired.
An even more inportant application is to display either alone or
superimposed on other patient data, other information, for example,
a freshly processed X-ray photograph where the camera 100 is
located in the X-ray process laboratory and one monitor is at
bedside or in an operating room. The surgeon may examine the X-ray
while operating without any physical transfer or handling of the
X-ray photograph.
The video mixer 114 also provides an additional function of
importance. It receives BCD data from the master keyboard 53, lead
112 and a date and time signal generator 120 via and auto update
controller 121. The keyboard allows the generation of BCD encoded
alpha numeric information such as the patients name, bed or
location, medication or special information. The date and time
generator 120 generates BCD signals representing actual time and
date. The auto update controller 120 automatically enters real time
date on lead 112, data and time data from generator 120, BCD A.M.
data on a lead 117, when present, and alpha numerics from keyboard
53 into the character generator portion of mixer 114 where they are
combined with the analog signals. The data is combined and
ultimately displayed on monitors 19 and 26 in the form represented
in FIG. 6 of the drawing.
The master keyboard 53 and the auto controller 121 also constitute
data sources for computer storage of patient data and thus are both
connected to a modem and interface circuit 122 for interconnection
with a computer, unshown in the drawing. The modem and interface
circuit 122 is selected for compatability with the BCD inputs and
whichever computer may be used by the hospital.
In addition to the direct cabled distribution to analog and alpha
numeric data to television displays, an RF distribution link may be
used. This is used by connecting the video display distribution
amplifier 115 over lead 123 to a video display selector switch 124
and in turn to, to an RF amplifier 125 and RF transmitter 126. The
tansmitter 126 is connected to transmitting antenna 56, unshown in
FIG. 4 but appearing in FIG. 2. Closed circuit TV input from
selector 116 may also be applied to the controller 124 for
distribution if desired.
Employing this last feature, any commercial television set within
range of the hospital antenna may display patient data as required.
As examples of ultimate applications, a patient's physician may
carry on other duties in the hospital while having either an AC
powered or portable battery powered television set in front of him
and observe real time physiological data of his patient. Where, as
often is the case, a physician may have his office in the hospital
or in a nearby building, he may proceed with his office schedule
while continuously monitoring a critical patient. Also employing
two other features of this invention this same physician may, from
his remote location, be alerted to abnormalities in the patient's
data and on command, have a printout of either an abnormality or
any desired date produced. These features are disclosed below.
The basic control at the central control station is the central
alarm selector 130 receiving power from the power supply and binary
coded data from the patients bedside via interface 102 and lead
113. The nurse or operator, under the direction of the patient's
physician, sets limits such as respiration rate, heart rate, blood
pressure, or whatever parameter is being monitored. The selector
130 is set to provide an alarm signal on lead 131 whenever such
limits are exceeded. This alarm signal is applied via interface
102, lead 112 to the auto update controller 112. When color
displays are employed, the signal from the auto update controller
121 is applied to change the trace color in the mixer 114, e.g.
from white to red. In the case of black and white monitors, it is
used to Z modulate the trace to provide a flashing or higher
intensity trace. Both may be combined, e.g. Z modulation plus color
modulation. Color sets then display a color change of brighter
intensity and black and white monitors, a brighter or flashing
display. Central alarm selector 130 is also connected to analog
recorder 32 to activate it upon any alarm condition. The recorder
thus produces a record of the analog signals at the time of the
alarm. Normally, the controller will reset after a preselected
period and recorder 32 will stop.
One additional feature of this invention involves an additional RF
link and control circuitry. As shown in FIG. 1, the central console
24 includes a remote receiver 34 with its antenna 35. A hand held
signalling device similar to a portable garage door opener
signalling device is employed. This signalling device transmits a
signal whenever it is within range of the receiver 34 (e.g. 300
feet.) The receiver 34 and remote control 40 may be single or
multiple channel but in either case an output signal is applied to
lead 131 to the interface circuit 102 and thence to the lead 132
and freeze control of the video converter 51. Thus operation of the
remote control 40 will freeze the image on all of the video
monitors allowing the physician to examine the trace for the freeze
period e.g. 30 seconds before the trace begins again.
The remote receiver 34, upon a freeze command, also applies a print
command signal over lead 133 to video input selector 134 and a
video printer 135 which prints an actual reproduction of the
present face of an internal monitor. Thus the physician regardless
of his location, when actuating the remote control 40 not only sees
the frozen pictures at that time but upon his next stop at the
control console may obtain a relatively high resolution print of
the frozen picture for examination or permanent record. Where the
signalling device is multichannel, its particular signal is
transmitted on to the video imput selector 134 which will allow
printing of only the required portion of the video display or will
mark the trace of interest.
The one additional feature of this invention involves the presence
of a central arrhythma detector 140, driven by analog signals on
lead 111 to detect arrhythma conditions, e.g. rhythm changes of the
heart. The central arrhythma detector produces, upon detection, an
alarm signal in BCD format on leads 145 and 146 and as a simple
alarm pulse on lead 150 to the remote receiver. The trace is then
frozen on video monitors and a printout made on printer 33.
One of the features of this invention is that despite the
flexibility and completeness of this system, its cost is
surprisingly low since it employs conventional television sets as
monitors, as compared with cardioscopes, and many of the components
are off-the-shelf items, available and used without change. When
combined in an integrated system, the advantages appear. Standard
elements making up the system are identified below:
__________________________________________________________________________
COMPONENT MANUFACTURER & ADDRESS MODEL
__________________________________________________________________________
Telemetry transmitter 104 Pacific Communications, System 75
Telemetry receiver 105 Inc. Santa Ana, Calif. Analog recorder 32
Gulton Industries, Inc. Mark 3 East Greenwich, R.I. Remote control
40 single & Linear Corporation Genie double Inglewood,
California 90301 b120 Remote receiver 34 Central Arrhythma Detector
Wolff Industries 788 San Marino, Calif. Master keyboard 53 Carmel
Electronics 10301- & Alpha update Los Angeles, Calif. 302-100
controller 121 R.F. Amp 125 & transmitter 126 Catel
Incorporated Mountain View, Calif. VN 1500 Mixer & video Mixer
114 Hughes Aircraft Co. MSC-1 and video translator 51 Oceanside,
Calif. Video Displays 19, 26 any conventional TV set or monitor
__________________________________________________________________________
Now referring to FIG. 6, in which a typical display 30 of FIG. 1 is
illustrated. It combines graphical representations of actual
patient data with alpha numerics identifying the patient by name or
bed number, date and time, vital parameters such as temperature,
pulse rate, medications or any other significant data which the
patient's physician may desire displayed. The data and one trace
from each of a number of patients may be displayed simultaneously.
A four patient display is illustrated in FIG. 6. As indicated
above, the display trace rate is controllable and freezable so that
rapid response data may be expanded for easier analysis by the
physician. As desired above, the trace may be frozen by remote
control. The display of FIG. 6 appears on the central control
console of FIG. 1 and may be transmitted via unused entertainment
channel to each of a number of entertainment television sets in
patient rooms or in doctor's offices or lounges. Thus, the
physician may see a real time display of his patients vital
parameters any place where an entertainment television set is
available. He may obtain a print of any interesting trace merely by
operating the portable freeze control. Where the display is on a
color television monitor, the normal trace may be in white and the
trace converted to a distinguishable color, e.g. red, when present
limits are exceeded.
Now referring to FIG. 7, a typical patient station module is
represented in this Figure. It is the pulse fail detector and pulse
rate detector employing Wheatstone bridge sensor 300 of any of the
several types available on the market, with two opposite junctions
connected to a differential amplifier 301 and the opposite
junctions connected between the regulated power supply from the
central station identified as SUPPLY 302, and a voltage regulator
303 to ground. A zero calibrated switch 304 is associated with the
sensor 300. The differential amplifier 301 is connected to an AF
amplifier 305 with an RF bypass resistor 306 and gain set control
310. An automatic zero set circuit 307 controlled by local zero set
switch 308 allows resetting to zero of the output any time by the
person at the patient station. The zero set circuit may include an
LED display 309 to indicate zero set condition. The output of the
amplifier 305 is connected in parallel to each of four parallel
stages 311 through 314. Stage 311 detects systolic rate. The stage
312 detects mean rate. Stage 313 detects diastolic rate and the
stage 314 responds to the pulse rate. Selector switches 315, 316
and 320 are connected with each of the stages 311, 312 and 313, and
the output of each of these is selectively connected via lead 321
to a BCD display 322 located at the patient station as illustrated
in FIGS. 1 and 2. Output leads 323 from the BCD display 322 are
connected via the cable 23 of FIG. 1 to the central control station
for display and usage at the central console. The mean rate from
stage 312 is also conveyed via lead 324 to an amplifier 325 and
associated upper and lower limit stages 326 and 330, each of which
are associated there with respective gates 331 or 332 and LED type
visual indicators 333 and 334, which show deviations from preset
limits by illumination of the appropriate LED. The output of the
stages 326 and 330 also are connected to a common gate 335 with
associated alarm 336 to give an alarm at any time either limit is
exceeded. Actual pulse rate, in addition to being conveyed to the
central station on lead 340 is amplified in amplifier 341 which
drives an LED 342, for example green in color, to provide a visual
indication of pulse rate. Each of the indicators of voltage supply
present in the circuit in FIG. 1 are connected to appropriate leads
from the central supply. No local supply is present.
FIG. 7 is representative of a typical patient module and, of
course, different particular modules will be used for different
parameters to be mentioned. Characteristically existing state of
the art sensors are used and the information handing circuitry for
making up the remainder of the module will be tailored to the
sensor output and the characteristics needed to be displayed.
Now referring to FIG. 8, the video translator 51 shown in block
diagram form is an analog electrical signal storage unit with
"nondestructive" readout. Analog input signals are introduced via
lead 110 and routed to a scan converter tube 202, where they are
"written" on the storage target T in the form of electrostatic
charge potentials. Since the electron beam is projected along the
"Z" (longitudinal) axis of the tube, the input signals, which
control beam density, are referred to as Z, or Z-axis signals. The
precise location on the storage target T to which the modulated
electron beam is directed is governed by "X" (fast) and "Y" (slow)
deflection signals applied to the electromagnetic deflection yoke
D.
The analog input signals constituting the information to be stored
may be fed to the video converter 50 in either a sequentially
acanned or a selectively positioned format. As examples, the former
deflection method would be a raster for accommodating television
images as from channel 100, while the latter deflection method
would be used to curve plots as from lead 110. The input deflection
mode is selected by applying either a RASTER WRITE or a GRAPHICS
WRITE command signal to the respective input terminals.
The key component upon which operation of video converter 51
depends is a scan converter tube 202, for example, Hughes Aircraft
Company, Oceanside, California, Type H-1268. It is an
electromagnetically focused and deflected cathode ray tube which
functions in a manner analogous to that of the familiar picture
tube, except that the electron beam is directed toward the
charge-storage target T, rather than a phosphor viewing screen. The
electron gun or K and deflection system are substantially the same
as those employed in any high quality cathode ray tube. The
operating modes of the scan converter tube 202 are WRITE, READ and
ERASE (and PRIME, if required); these operating modes, and the
methods by which they are carried out, are explained in detail in
subsequent paragraphs.
The essential component parts of tube 202, shown in simplified form
in FIG. 8, are the electron gun K, collimator C, collector P and
storage target T, the latter two elements comprising the storage
target assembly, plus the associated focus coil F and deflection
yoke D. The metallic grid-like portion of the storage target is
commonly referred to as the "storage mesh" (also as the "backing
electrode") and, since output signals are taken from this tube
element, it is designated the "signal output electrode."
The essential central elements of video translator 51 and the
principal signal and power paths among them are shown in the
functional block diagram, FIG. 8. For convenience of explanation,
these elements are organized into five groups: (1) Timing circuits,
(2) Deflection circuits, (3) Scan Converter tube electrode
switching circuits (all electronic switching), (4) Video circuits,
and (5) Power supplies, including the static focus current
supply.
The timing circuits, by means of which the converter 51 carries out
its prescribed writing (and priming), reading and erasing
functions, at the proper times and for the proper durations, are
comprised of the program section which includes control logic
circuitry 200 and the Sync Separator/Counter 201. The Sync
Separator 201 is active when externally supplied composite 525-line
60 Hz or 625-line 50 Hz sync is used; under this condition, the
internal counter is disabled. Otherwise, the Unit is synchronized
by the internal 525-line 60 Hz line-locked counter.
Deflection circuits, which govern the scanning pattern and sweep
rate of a scan converter tube 202 electron beam consist essentially
of the X and Y deflection generators 203 and 204, and their
associated deflection amplifiers 205.
The tube electrode switching circuits change scan converter tube
202 operating conditions in accordance with incoming mode commands:
RASTER WRITE, GRAPHICS WRITE, RASTER ERASE, SELECTIVE ERASE, and
when used, PRIME. In the absence of any of these commands, the
circuits automatically switch operating conditions of the scan
converter tube 202 to READ mode. Switching signals, derived from
mode command signals in the program section are routed to five
switching circuits: (1) Focus switch 206, (2) Deflection switch
207, (3) Bias switch 210, (4) Storage mesh switch 211, and (5) the
Write video amplifier and cathode switch 212.
The focus switch 206 changes the d.c. voltage of the electrode of
the tube 202 in the WRITE and SELECTIVE ERASE modes. By means of
this small correction in writing and selective erasing, optimum
beam focus is maintained in all modes.
The deflection switch 207 effects prescribed changes in scan
converter tube 202 beam scanning for the various modes. For
example, if externally deflected writing and internally deflected
reading are used, the deflection switch 207 connects signal paths
from the external deflection input terminals to the deflection
amplifiers 205 in the WRITE mode, and from the internal X and Y
deflection generators 203 and 204 to the deflection amplifiers 205
in READ mode. Deflection switching is required wherever scanning
schemes differ with respect to format, scanning axis, scanning rate
or polarity.
Since, among the various modes, the scan converter tube 202 is
operated at several different electron beam energy levels, a means
is required to establish optimum beam intensity for each mode. This
requirement is met by changing control grid bias levels, a function
carried out by the bias switch 210.
The storage mesh switch 211 and the cathode switch 212, which
latter is an integral part of the write video amplifier, act in
concert to set the scan converter tube 202 electron beam level
corresponding to a particular mode command. The storage mesh switch
211 effects appropriate changes in the storage mesh of the tube 202
(also referred to as "backing electrode") d.c. operating level and,
at the same time, the cathode switch places the proper d.c. voltage
on the converter tube 202 cathode. Additionally, the write video
amplifier 212 is enabled only in the RASTER WRITE, GRAPHICS WRITE
and when used, PRIME modes. Beam modulation is applied in the WRITE
modes but not in PRIME mode.
Video Circuits include the write video amplifier 212, read video
preamplifier 213, and read video post amplifier 214. The write
video amplifier 212 raises input video amplitudes to proper levels
for application to the scan converter tube 202, while the post
amplifier 214 adds sync and blanking signals to the video, and
mades the composite signal available to READ VIDEO OUTPUT Jack
215.
For a more complete explanation of the operation of the Hughes Type
Scan Converter, reference should be made to the Instruction Manual
of Model MSC-1, available from the Hughes Aircraft Company,
Industrial Products Division, Oceanside, Calif.
The above described embodiments of this invention are merely
descriptive of its principles and are not to be considered
limiting. The scope of this invention instead shall be determined
from the scope of the following claims, including their
equivalents.
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